Hello,

First motor that's bringing me into the LS world, putting this engine in my firebird, and want to make sure it looks managable. I'll attatch some images, long story short, 03 LM4 (aluminum 5.3), found in trail blazers engine bay as pictured on its side already pulled for unknown length of time. Was said to be running and driving when it came into the yard, over all condition I would assume it was, to what degree, to what strength, not sure, but condition does lead me to believe it was running.

With that said, sitting on its side with an exhaust valve open let some water into cylinder 6, and need opinions of if I should be concerned at all. Obviously with any amount of money almost anything without a blown hole in the side can be restored, but I don't want to spend a ton of money on this block to run it.

Images linked show it before I did anything but pull the head...then I turned the motor over and it cleaned up drastically, almost unnoticeable, but looking at it there is still half of inch of the surface rust on the side wall. Not sure if just a hone, and maybe some new rings and everything would be back to good. I know it's subjective opinions, but anyone that has seen something like this please give me insight if it shouldn't be too much of a chore to run this block or if I should return this to the yard. As to the rest of the cylinders, high amount of carbon deposits on cylinder head combustion area, but otherwise cylinder walls still have cross hatching from when new. I intend to replace the heads with better flowing stock heads so just concerned about the block. I plan on flipping over and pulling the oil pan to see the bottom, just gauging concern of cylinder 6 from the top. Thanks!

 

Anyone?

 

Cylinders look pretty rusty but not pitted per say. I would tear it down and run a ball hone through it, not a 3 stone hone! If they clean up great, if not you're looking at boring .030 and new oversized pistons and rings.

 

This is just me.. if it were mine engine, id totally just hone it a bit, hit some 45 cross hatch on it, inspect the rings clean them and the land groves and or buy new rings if needed and throw it back together

If you take off too much with the hone, you will get piston rock, but it will just be a bit noisy is all, but i doubt you will have to take much off to get passed the rust..

Now if you have the money, do it right !!! just take it to a engine shop and let them do what is needed

But yeah to answer your question, to me, the engine looks ok, but hard to really tell by pics for sure... bore gauge it, there is a PDF for the LQ4/LQ9 floating around here somewhere.. if you can't find it let me know, ill upload it to ya .. and if you don't have a bore gauge, get the pistons all out, clean them up, get the rings off be careful not to break the 2nt ring, they are easy to break, keep them in order and right sides up just in case and clean up your cylinder bore, hone it a bit tell rust is gone, use a filler gauge, put between piston inside the cylinder bore, make sure to measure on the skirt of the piston not up by the land/ring groves and if its in spec your good to go, but even if its a tad bit over spec id still say good to go but no more than 0.004 maybe 5 but at 6 it will have way too much piston rock, service limit is 0.0032

EDIT: Sorry i missed the words LM4 aluminum 5.3, so sorry But the piston to bore service limit is more like 0.0028 for the aluminum 5.3 blocks, so wouldn't go over bout 0.0035.. i do not know much about aluminum blocks and i had to search out the specs to come correct my reading error..

But me id still totally go 0.004 and be ok with it but with the cylinder liners, i don't know, too much piston slap might cause it to crack or wear more then an iron block.. and the expansion im sure is totally different..

neways yeah man hope this helps ya ah and if ya wanta see my hone on a 5.3 check out

 

Running the piston up and down cleaned 90% of it in its path, and if I looked away and felt it I couldn't tell you where the rust was, it was that smooth. with that said, two cylinders have these marks on the side walls towards the valley cover, is this when they are out of spec? or just maybe some debris in rings that I made the marks turning it over? I don't mind spending a little money on the block, just don't want to spend thousands on a full rebuild if I can help it.

 

Thank you for the video, just had a chance to watch it, was very insightful. going to go through it more thoroughly, just trying to do a visual quick to make sure i don't see anything because the motor warranty is up next Friday and I have to go out of state for a business trip so don't have a lot of time to do measurements. With that said from what I've read, this motor can be punched out to 5.7 so I feel pretty confident that if nothing is cracked or obviously bad, that I should have a thick enough liners that things can be repaired. Just was concerned about the surface rust.

Quick question, what is the different application of a ball hone and a 3 bar hone?

 

I think maybe preference and cost and also, i think with the ball you get a better cross hatch, but, i think the ball type just contours to the cylinder wall, so out of round = still out of round and low or high spots stay there vs the 3 bar, i think it helps to even things out more... 80 to 120 bucks vs 15 to 25

And yeah, heck id totally run it as is, if id had the engine still in the vehicle with only head off, but since its out, i do a cross hatch on them all just enough to clean them up and run with it, else your going to spend money on new pistons, rings and machine shop time and so on and so forth ..

Yep more than likely its just something/rust stuck in the rings or between the wall and piston..

Or it could be the land/ring groves are full of carbon or rust got in behind them and not allowing the rings to fully seat in the land/ring grove completely and the ring gap isn't siting down all the way and is causing the scratches from the ring butt ends, but really i doubt it..

Edit: Sorry again, lol opps, yeah you said 2 of the pistons have those marks in the same place, if so, then its more than likely just carbon or something behind the rings in the land groves not allowing the rings to seat fully..

neways yeah hope that helps peace

 

yup that helps me feel a little bit better. long story short, I'm restoring the body of an 86 trans am, and putting all new power train in, i like the idea of aluminum block for weight savings, not looking to go wild with it, keeping it a NA motor, and with that, think that this would be a great platform. From what I've read, this being an earlier block, thicker sleeves lets me have some room for punching in the future should it prove to need it, but would like to run it as is for now. Want to put down around 400 hp, closest to that for rwhp through a 4L60e would be ideal since I don't like where the cost of T56s are going. This is going to be a project that will take me into possibly early 2017 for completion with the body I need to take care of first, so just want to make sure that this thing looked okay to run before the warranty to return it ran out. I'm going to pull the bottom end and make sure nothing is obviously wrong down there and then seal it up and store it. For a motor that was already in a junk yard already pulled before i got there, and with the a/c, gas pedal for DBW, harness and pcm, for $280, I couldn't say no.